Apparatus for exothermic catalytic reactions with integral heat exchanger



Oct. 28, 1969 1 5, uo ET AL 3,475,137

APPARATUS FOR EXOTHERMIC CATALYTIC REACTIONS WITH INTEGRAL HEAT EXCHANGER Filed March 9. 1967 4Sheets-Sheet 1 CHI SHENG KUO AXEL CHRISTENSEN INVENTORS BY al al 2%; AGENT 0a. 28, 1969 A I CH,

APPARATUS FOR EXO 4 Sheets-Sheet 2 Filed March 9. 1967 CH! SHENG KUO AXEL CHRISTENSEN INVENTORS I W Oct. 28, 1969 APPARATUS FOR EXOTHERMIC CATALYTIC REACTION Filed March 9. 1967 CHI 5. KUO ET AL s WITH INTEGRAL HEAT EXCHANGER 4 Sheets-Sheet 5 CHI SHENVG KUO AXEL CHRISTENSEN INVENTOR-S Oct. 28, 1969 CHI 5. KUO ET AL 3,475,137

APPARATUS FOR EXOTl'IERlAIC CATALYTIC REACTIONS WITH INTEGRAL HEAT EXCHANGER Filed March 9. 1967 4 Sheets-Sheet 4 CHI SHENG KUO AXEL CHRISTENSEN I N VENTORS United States Patent 3,475,137 APPARATUS FOR EXOTHERMIC CATA- LYTIC REACTIONS WITH INTEGRAL HEAT EXCHANGER Chi S. Kuo, Mount Kisco, N.Y., and Axel Christensen, Stamford, Conn, assignors to Chemical Construction Corporation, New York, N.Y., a corporation of Delaware Filed Mar. 9, 1967, Ser. No. 621,949 Int. Cl. B015 9/04 U.S. Cl. 23289 19 Claims ABSTRACT OF THE DISCLOSURE A heat exchange apparatus for exchanging heat between a hot reacted fluid stream derived from a high temperature exothermic catalytic reaction and a cold feed fluid stream to a high temperature exothermic catalytic reaction. The apparatus features elements which provide cooling of the vessel walls and countercurrent heat transfer between the hot and cold fluid streams, as well as elements for addition of a cold bypass fluid stream to the heated feed stream for temperature regulation. An integral combination of the heat exchanger with a catalytic converter is also provided.

BACKGROUND OF THE INVENTION Field of the invention The invention relates to apparatus for exothermic catalytic reactions such as the high pressure catalytic synthesis of ammonia or methanol, in which the cold feed fluid stream to catalytic synthesis must be heated by heat exchange with the hot reacted fluid stream from the synthesis vessel, prior to passing the feed stream to catalytic synthesis in which the exothermic reaction takes place. Numerous exothermic catalytic reactions require preheat of the feed fluid stream to optimum or minimum ignition temperature, prior to passage of the feed stream in contact with the catalyst bed. In many of these processes, the temperature of the heated feed stream must be moderated or controlled by the addition of a cold quench or bypass feed stream. The heat exchanger apparatus combination of the present invention performs these functions in a highly eflicient manner.

Description of the prior art Disclosures of the general concept of external heat exchange between process streams of catalytic converters are provided in U.S. Patent Nos. 3,067,017; 3,002,816; 2,078,948 and 2,032,652. In addition, catalytic reactors of various designs with internal heat exchange sections are provided in U.S. Patents Nos. 3,212,862; 3,050,377; 3,041,151; 2,853,371; 2,512,586; 2,252,667 and 2,032,652.

SUMMARY OF THE INVENTION In the present invention, an apparatus is provided for integrated heat exchange between the hot reacted eifluent fluid stream from a catalytic converter and the cold feed fluid stream to the catalytic converter, which is applicable to processes in which an exothermic catalytic reaction takes place in the catalytic converter. The apparatus features a lower heat exchange section in which heat transfer takes place through a plurality of vertical heat exchange tubes which extend between openings in parallel opposed horizontal baflies. The heat exchange section is enclosed by a fluid circulation plate within the heat exchanger vessel, and cold feed fluid is circulated between the plate and the vessel wall to provide cooling, which protects the vessel wall and closures such as gasket seals from excessive temperature. The warmed feed fluid is ice moderated and controlled in temperature by the provision of a bypass cold feed fluid inlet conduit, which extends vertically downwards into the heat exchanger vessel above the heat exchange section and serves to pass cold bypass fluid into the warmed feed fluid stream discharged upwards within the vessel from the lower heat exchange section.

An integrated combination of the heat exchanger apparatus and its associated catalytic converter is also provided, in which the various process fluid streams flow alternately between the apparatus units so as to provide optimum circulation and cooling effects. This integrated combination apparatus attains cooling of both the catalytic converter and the heat exchanger vessel by the circulation of appropriate cold process fluid streams between circulation plates disposed in each vessel and the respective vessel wall.

A primary advantage of the invention is that the cold feed fluid stream being passed to exothermic catalytic conversion is employed to cool the high pressure vessel of the exchanger, which permits the economical use of high strength carbon steel for the vessel. Another advantage of the apparatus arrangement of the invention is that it requires the shortest and simplest pipe lines to and from the converter because of the closeness among the connecting nozzles and because of the negligible differential thermal expansion between the converter and the exchanger vessel shells. An estimate indicates that for a 2000 tons per day methanol synthesis facility, the saving in the massive high pressure and high temperature pipes and fittings will exceed $80,000. Another advantage is that the upper plenum of the exchanger is utilized as a cold bypass fluid mixer for controlling the warmed feed fluid temperature entering the catalyst bed in the converter vessel. If the mixing arrangement and apparatus of the present invention was omitted, an externally located high pressure mixer would have to be provided. This extra mixer would have to be insulated both internally and externally and would cost as much as a medium size high pressure separator. An additional advantage of the invention is that the arrangement of apparatus elements in the heat exchanger vessel, and the shortening and simplifying of piping both internally and externally, results in a lower pressure drop for the circulating fluid streams, which thereby lowers power requirements for fluid recirculation. A further advantage is that the heat exchanger arrangement permits test and repair of leaking heat exchange tubes at the plant site, since the tubes are readily removable for inspection, testing and repair in the field. The heat exchanger apparatus maintains fluid counterflow for effective heat exchange. These advantages mentioned supra become more pronounced as the required size of the facility and apparatus units increases.

Another advantage of the invention is that all of the large size high pressure fluid closure in the apparatus are protected against exposure to high temperature. In a typical ammonia synthesis facility, all of the closure components in the apparatus are kept below a temperature of 230 C., instead of the temperatures of up to 500 C. encountered in prior art arrangements. Serious leakage is frequently encountered when closure seals are subjected to a combination of high pressure and high temperatures. When such a seal develops leakage, it is almost always impossible to make the closure fluid-tight again by simply re-tightcning the closure bolts. In order to repair a leaky closure seal or joint in high pressure-high temperature service, it is usually necessary to repeatedly shut down and restart up the immediate facility or the entire chemical plant, which results in costly loss of production. Finally, keeping the closures at relatively lower temperatures is also advantageous because the bolting requirements are reduced, which therefore permits lighter closure construction. This advantage consequently results in cost savings in closure construction.

It is an object of the present invention to provide an improved heat exchanger apparatus for exchanging heat between a hot reacted fluid stream derived from a high temperature exothermic catalytic reaction and a cold feed fluid stream to a high temperature exothermic catalytic reaction.

Another object is to provide an improved apparatus for exothermic catalytic reactions with integral heat exchanger and improved fluid circulation between vessels.

A further object is to provide a heat exchange apparatus in integrated combination with a catalytic converter for exothermic catalytic reactions, in which the heat exchange apparatus serves to exchange heat in an improved manner between the hot reacted fluid stream derived from the converter and the cold feed fluid stream to the converter.

An additional object is to provide a heat exchange apparatus for heat exchange between fluid streams passing to and from anexothermic catalytic reaction, in which the cold feed gas passing to the reaction is employed to cool the heat exchanger vessel.

Still another object is to provide a heat exchange apparatus for exothermic catalytic reactions in which the temperature of the warmed feed gas produced in the heat exchange apparatus is moderated and controlld within the apparatus by addition of a cold bypass feed fluid stream.

Still a further object is to provide a heat exchanger apparatus for heat exchange between fluid streams passing to and from an exothermic catalytic reaction in which fluid pressure drop in the heat exchanger apparatus and between the heat exchanger apparatus and between the heat exchanger apparatus and the catalytic converter is reduced.

An additional object is to provide a heat exchange apparatus for heat exchange between process fluid streams in an exothermic catalytic reaction, in which closure seals and gaskets are protected against exposure to highly elevated process stream temperatures by the arrangement of the apparatus elements in the heat exchanger apparatus.

These and other objects and advantages of the present invention will become evident from the description which follows.

DESCRIPTION OF THE DRAWINGS AND PREFERRED EMBODIMENTS Referring to the figures:

FIGURE 1 is an overall elevation view of the heat exchanger apparatus of the present invention, showmg preferred embodiments of the invention in combination,

FIGURE 2 is a sectional plan view of FIGURE 1, taken on section 22,

FIGURE 3 is a partial sectional elevation view of an alternative embodiment of the heat exchanger apparatus, and

FIGURE 4 is a flowsheet showing process fluid streams and the integral combination of the heat exchanger apparatus with a catalytic converter for exothermic catalytic reactions and other process units, in a typical application of the invention to the catalytic synthesis of methanol or ammonia.

Referring now to FIGURE 1, the heat exchanger apparatus of the invention is defined by the vertically or ented vessel 1 which usually consists of a high pressure shell. A vertical fluid circulation plate 2 is disposed within and adjacent to the inner wall of vessel 1. Plate 2 extends upwards to upper central conduit 3 which serves to transfer warmed feed fluid upwards from the lower heat exchange section of the unit. In addition, plate 2 is provided with a least one lower opening such as 4 for feed fluid transfer. An upper substantially horizontal baflle 5 is centrally disposed within vessel 1 and inside the plate 2. Bafiie 5 serves to define the uppermost section of the heat exchange portion of the unit. A baflle 6 is disposed below and parallel with the baflle 5. Baflle 6 is provided with a central opening 7 and a plurality of additional spaced apart openings 8. A vertical closure partition 9 extends between the outer edges of batfles 5 and 6 t provide fluid closure. A baflle 10 is disposed below and parallel with the baflle 6, and is provided with a central opening 11 and a plurality of additional spaced apart openings 12. Each of the substantially vertical heat exchange tubes 13 extends between one of the openings 8 in the baflle 6 and one of the openings 12 in the battle 10. The heat exchanger section is completed by the lower baflle 14, which extends horizontally below and parallel with baflle 10 and is provided with a central opening 15. A vertical closure partition 16 extends between the outer edges of battles 10 and 14 to provide fluid closure.

A hot fluid inlet conduit 17 is vertically and coaxially disposed within the vessel 1, and extends centrally upwards from the lower end of vessel 1 through the central openings 15 and 11 in baflles 14 and 10 respectively, to the central opening 7 in baflle 6. Conduit 17 is contiguous with the central opening 11 in baflle 10, and an external packing joint 88 is provided between these elements for fluid sealing. A hot reacted fluid stream 18 derived from a high temperature exothermic catalytic reaction is passed via inlet nozzle 19 into the lower end of vessel 1, and flows between insulation layers 20 and 21, and into the lower end of conduit 17. The hot fluid stream 18 next flows upwards through conduit 17, laterally outwards between baflles 5 and 6, downwards into and through heat exchange tubes 13 for cooling by heat exchange with cold feed fluid stream, and laterally inwards as cooled reacted fluid stream between baffles 10 and 14. The cooled reacted fluid stream flowing inwards between batfles 10 and 14 next flows into the vertically oriented cooled fluid outlet conduit 22, which is coaxially disposed external to conduit 17 and extends downwards from opening 15 in baffle 14. Additional horizontal fluid diversion baflles 23 and 24 are provided as required, and insulation layers 25 and 26 are also preferably provided to prevent temperature elevation of the packed joints 27, 28 and 29. The cooled reacted fluid stream flows through the lower outlet of conduit 22 and between insulation layers 25 and 26, and is discharged via nozzle 30 as stream 31. Baflle 32 extends horizontally between the wall of vessel 1 and conduit 17, and serves to support the packed joints 28 and 29 and to provide for fluid sealing between stream 18 and 31.

A cold feed fluid stream 33, which is to be subsequently passed to an exothermic catalytic reaction, is passed via nozzle 34 into vessel 1 external to plate 2 and adjacent to the upper end of the plate 2. The cold feed stream flows downwards between plate 2 and the wall of ves e 1, theresby cooling the side wall of the vessel 1. The cold feed stream next flows inwards and upwards through the lower opening 4 in the plate 2, and upwards between Plate 2 and the vertical closure partition 16. The cold feed stream next flows upwards external to the heat exchange tubes and is thereby heated. Horizontal fluid diversion baflles 35, 36 and 37 are preferably provided to impart a lateral flow direction to the cold feed gas external to the tubes 13. Baflles 35 and 37 are substantially horizontal and extend inwards from plate 2 and between baflles 6 and 10, and extend external to the heat exchange tubes 13, terminating adjacent to conduit 17. Baffle 36 is substantially horizontal and extends outwards from conduit 17 and between baffles 35 and 37, and extends external to the heat exchange tubes 13, terminating adjacent to plate 2.

The feed fluid stream flowing laterally and upwards external to tubes 13 is heated, and flows outwards from the heat exchange section between baflles 6 and 37, and next flows upwards between plate 2 and partition 9. The warmed feed fluid stream then flows upwards and is diverted by the upper curved section of plate 2 into the upper central warmed fluid transfer conduit 3, which is preferably provided with internal insulation lining 38. The conduit 3 is preferably centrally disposed and coaxial with vessel 1. Bypass cold feed fluid inlet conduit 39 extends vertically downwards into vessel 1 from an upper inlet above conduit 3, and in this embodiment of the invention, the conduit 39 is centrally and coaxially disposed with respect to vessel 1. Bypass cold feed fluid stream 40 is passed via nozzle 41 and conduit 39, and stream 40 flows downwards through conduit 39 and is discharged into the rising warmed feed fluid in conduit 3 through the foraminous lower end of conduit 39. The resulting combined mixture of warmed feed fluid and cold bypass feed fluid is removed from the upper end of vessel 1 via outlet nozzle 42 as stream 43. The flow rate of stream 40 is regulated and varied so as to control and moderate the temperature level of stream 43 as required. The conduit 44 extending between vessel 1 and nozzle 42 is provided with internal insulation layer 45. Keyed or gasketed closures such as 46 may be provided between the cover and vertical body sections of vessel 1, and a packed joint 47 is provided between conduit 3 and the upper section of vessel 1.

Referring now to FIGURE 2, a sectional view of FIG- URE 1 taken on section 22 is shown. FIGURE 2 illustrates a preferred embodiment of the invention, in which vessel 1, plate 2 and the conduits such as 17 are cylindrical and coaxial, and the baffles such as 36 are circular. In addition, the cylindrical heat exchange tubes 13 are shown in circular section, and disposed in radial rows.

FIGURE 3 illustrates an alternative embodiment of the invention, in which the cold bypass feed fluid stream 40 is added to the warmed feed fluid stream above conduit 3, and in a top section of vessel 1 defined by insulation layer 38. The removal of the resulting feed gas mixture 43 takes place on the opposite side of vessel 1, from FIGURE 1. In addition, two heat exchange tubes 13 are shown on each side of central inlet conduit 17, while in the case of FIGURE 1, three tubes were provided in each row of tubes 13. The number of tubes 13 in each row of tubes, and the arrangement of the tubes 13, depends on design considerations for a particular facility. In some instances, the tubes 13 may be arranged in coaxial circular banks of tubes, with juxtaposed tubes being equally spaced apart in each bank. FIGURE 3 also shows details of a packing joint, in which the sleeve 48 is forced downwards against the packing 49 by nut 50, which is tightened onto bolt 51. FIGURE 3 illus- Hates the weld elements 52 and 53 which join closure partition 9 to baffles 5 and 6 respectively. Finally, closure ring or gasket 46 extends between vessel body 1 and high pressure closure plate 54.

FIGURE 4 illustrates apparatus and a process flowsheet showing the integral combination of the heat exchanger apparatus with a catalytic converter for exothermic catalyst reactions and other process units, in a typical application of the invention to the catalytic synthesis of methanol or ammonia. FIGURE 4 will be described relative to catalytic ammonia synthesis, however it will be evident that the arrangement of FIGURE 4 is equally applicable to the catalytic synthesis of methanol or other exothermic catalytic reactions. Referring now to FIGURE 4, the exothermic catalytic synthesis of ammonia by reaction between nitrogen and hydrogen takes place in the vertically oriented reactor vessel 55 which is provided with an internal vertical fluid circulation plate 56 adjacent to its inner wall. Catalyst beds 57 and 58 are disposed in series within the vessel 55, with the outer perimeters of the beds 57 and 58 being defined by the plate 56. Beds 57 and 58 consist of any suitable ammonia synthesis catalyst, such as iron oxide, promoted with such agents as aluminum oxide and potassium oxide. Other promoters include zirconium oxide, chromia and calcium oxide. The warmed feed synthesis gas stream 43, consisting principally of nitrogen and hydrogen in a 1:3

molar ratio, is passed into vessel through nozzle 59 and flows downwards within plate 56 and through beds 57 and 58 in series, with exothermic catalytic synthesis of ammonia taking place in each bed. Interbed quenching of the hot partially reacted gas stream between beds 57 and 58 is attained by injection of quench gas stream 60 via nozzle 61 into the main process gas stream. The resultant hot reacted gas stream 18 is removed from unit 55 below bed 58 via nozzle 62, and principally contains nitrogen, hydrogen and ammonia vapor.

Stream 18 passes via nozzle 19 into heat exchanger vessel 1, and thereafter flows upwards through central conduit .17 and downwards through heat exchanger tubes 13 and is cooled. The resultant cooled reacted gas stream 31 is removed from unit 1 via nozzle 30, and is passed to further processing for further heat recovery and separation of product ammonia by selective condensation. Stream 31 is first passed into steam boiler 63, and is cooled by heat exchange with boiler feed or condensate water admitted via stream 64, with produced process steam removal via stream 65. The resultant process steam 66 discharged from unit 63 is further cooled in heat exchanger 67 by heat exchange with condensate or boiler feed water stream 68, which is thereby warmed and discharged as hot water stream 69. The resultant process stream 70 discharged from unit 67 is further cooled in feed gas preheater 71 by heat exchange with recycle synthesis gas. The cooled process gas stream 72 discharged from unit 71 is now further cooled for selective liquid ammonia condensation in condenser 73, with cooling medium being admitted via stream 74 and warmed liquid or vaporized refrigerant being removed via stream 75. The resulting mixed gas-liquid process stream 76 is passed into gas-liquid separator 77, which is any suitable device for separation of gaseous and liquid phases, such as a baflled or cyclonic unit. Product liquid ammonia stream 78 is passed from unit 77 to product utilization, while residual synthesis gas stream 79, which will usually contain a minor residual proportion of uncondensed ammonia vapor, is recycled for further ammonia synthesis.

Stream 79 is first combined with make-up synthesis gas stream 80, which principally consists of nitrogen and hydrogen in a 1:3 molar ratio. The combined synthesis gas stream 81 now constitutes the feed gas to the ammonia synthesis converter, which must be warmed to a suitable temperature in order for the catalytic synthesis reaction to take place. Stream 81 is divided into bypass cold feed gas stream 40 and the main feed gas stream 82. Stream 82 is warmed in unit 71, and the resulting warmed feed gas stream 83 is divided into bypass quench gas stream 60, described supra, and the principal feed gas stream 84 which is utilized for vessel cooling in both units 55 and 1. Stream 84 flows via nozzle 85 into the space between vessel shell 55 and plate 56, and then flows upwards between shell 55 and plate 56 to provide a cooling effect. The feed gas stream is discharged from unit 55 via nozzle 86 as stream 33, which flows via nozzle 34 into unit 1. The feed gas next flows downwards between the wall of vessel 1 and plate 2, and upwards external to tubes 13, and is diverted laterally by horizontal baffle 87 which extends inwards from plate 2. The feed gas stream is thereby warmed by heat exchange with the reacted gas flowing downwards through heat exchange tubes -13, as described supra. The resulting warm feed gas stream flows upwards into conduit 3, and is I mixed with cold bypass feed gas stream 40, which is adconduit 39 has been shown as terminating within the upper central warmed fluid transfer conduit 3 in FIG- URE 1, however FIGURE 3 illustrates an alternative embodiment of the invention in which conduit 39 terminate above conduit 3. The removal conduit 44 will preferably be disposed above the lower terminus and forami nous openings of conduit 39, as shown in FIGURE 1, however conduit 44 may alternatively extend from below conduit 39 as shown in FIGURE 3. The lower end of the cooled reacted fluid outlet conduit 22 will preferably terminate above the lower end of the hot fluid inlet conduit 17, however conduit 22 may alternatively terminate below the lower end of conduit 17 and extend to nozzle 19, which in this case would serve as the means for cooled reacted fluid discharged from the vessel 1. In this case, conduit 17 would extend to nozzle 30, which would then serve as the means for hot reacted fluid inlet into the vessel 1.

As illustrated in FIGURE 4, in some cases only one substantially horizontal fluid diversion baffle 87 may be provided in the heat exchange section of unit 1 and external to tubes 13. In other instances, a plurality of staggered substantially horizontal fluid diversion baflles may be provided between baflies 6 and 10, with the fluid diversion baffies alternately extending inwards from plate 2 and outwards from hot fluid inlet conduit 17, and external to heat exchange tubes 13.

As illustrated in FIGURE 2, the vessel 1 and plate 2 are preferably cylindrical and coaxial, with the conduits being cylindrical and coaxial with the vessel, and with the baflies 5, 6, 10 and 14 and the fluid diversion bafliles 35, 36 and 37 being circular. Alternatively, in some instances the vessel 1 and internal components may be square, restangular or hexagonal or of any other suitable configuration in horizontal cross-section.

Although the apparatus of the present invention is preferably described as being applicable to ammonia synthesis, in which the cold feed fluid stream to exothermic catalytic reaction consists of ammonia synthesis gas principally containing nitrogen and hydrogen in a approximate 1:3 molar ratio, the invention is equally applicable to methanol synthesis or to other exothermic catalytic reactions, either in the gaseous or the liquid state.

The bypass cold feed gas inlet conduit 39 has been shown as being foraminous adjacent to its lower end. In some instances, it may be preferable to alternatively provide conduit 39 with a single fluid outlet such as a lower elbow which curves to a horizontal opening, or to merely provide conduit 39 with a single bottom opening.

In some instances, depending on pressure and temperature levels, streams 70 or 72 or both may contain a condensed liquid phase. In this case, the process streams 70 or 72 would preferably be passed through a gas-liquid separator similar to unit 77, to remove a liquid partial product stream. Finally, stream 81 will usually be passed through a recirculating blower or compressor, to compensate for uuid drop through the apparatus units and system.

We claim:

1. A heat exchanger for exchanging heat between a hot reacted fluid stream derived from a high temperature exothermic catalytic reaction and a cold feet fluid stream to a high temperature exothermic catalytic reaction which comprises a vertically oriented vessel; a vertical fluid circulation plate adjacent to the inner wall of said vessel; said plate extending to an upper central warmed fluid transfer conduit within said vessel and having at least one lower opening; an upper first substantially horizontal baflle within said vessel; a second baflle below and parallel with said first baflle, said second baflie being provided with a central opening and a plurality of spaced apart openings; a first vertical closure partition, said first partition extending between the outer edge of said first baffle and the outer edge of said secondbaffle; a lower third substantially horizontal baffle within said vessel, said third baffle being below and parallel with said second baflie and being provided with a central opening and a plurality of spaced apart openings; a plurality of heat exchange tubes, each of said tubes extending between one of said spaced apart openings in said second baflle and one of said spaced apart openings in said third baflle; a fourth baflle below and parallel with said third baflle, said fourth baffle being provided with a central opening; a second vertical closure partition, said second partition extending between the outer edge of said third baifle and the outer edge of said fourth bafllle; a hot fluid inlet conduit, said inlet conduit being vertically and coaxially disposed within said vessel and extending centrally upwards from the lower end of said vessel through said central openings in said third and fourth batfles to the central opening in said second baflle and being contiguous with the central opening in said third baifle; means to pass said hot reacted fluid stream derived from a high temperature exothermic catalytic reaction into the lower end of said inlet conduit, whereby said hot fluid stream flows upwards through said inlet conduit, laterally outwards between said first baflle and said second bafiie, downwards through said heat exchange tubes for cooling by heat exchange with said cold feed fluid stream, and laaterally inwards between said third baflle and said fourth baffle; a vertically oriented cooled fluid outlet conduit, said cooled fluid outlet conduit being coaxially disposed external to said hot fluid inlet conduit and extending downwards from said central opening in said fourth baflle; means for cooled reacted fluid discharge from said vessel disposed at the lower outlet of said cooled fluid outlet conduit; means to pass said cold feed fluid stream into said vessel external to said plate and adjacent to the upper end of said plate, whereby said cold feed stream flows downwards between said vessel and said plate thereby cooling the side wall of said vessel, inwards through said lower opening in said plate, upwards between said plate and said second vertical closure partition, upwards external to said heat exchange tubes for heating of said cold feed fluid stream, upwards between said plate and said first vertical closure partition, and upwards through said upper central warmed fluid transfer conduit, said warmed fluid transfer conduit being coaxial with said vessel; a bypass cold feed fluid inlet conduit, said bypass conduit extending vertically downwards into said vessel from above said upper central warmed fluid transfer conduit, said bypass conduit being provided with at least one opening adjacent to its lower end; means to pass a bypass cold feed fluid stream into said bypass conduit, whereby said bypass fluid stream passes into the warmed feed fluid stream flowing upwards through said upper central warmed fluid transfer conduit; and means at the upper end of said vessel to remove the resulting combined feed stream consisting of a mixture of bypass feed fluid stream and warmed feed fluid stream.

2. The apparatus of claim 1, in which said bypass cold feed fluid inlet conduit is coaxial with and terminates within said upper central warmed fluid transfer conduit, and said means to remove the resulting combined feed stream from said vessel is above the lower end of said bypass cold feed fluid inlet conduit.

3. The apparatus of claim 1, in which said bypass cold feed fluid inlet conduit is foraminous adjacent to its lower end.

4. The apparatus of claim 1, in which the lower end of said cooled fluid outlet conduit terminates above the lower end of said hot fluid inlet conduit, and said means for cooled reacted fluid discharge from said vessel is above said means to pass hot reacted fluid into the lower end of said inlet conduit.

5. The apparatus of claim 1, in which at least one substantially horizontal fluid diversion bafllle is provided within said vessel, said fluid diversion batfle extending 9 outwards from said hot fluid inlet conduit and between said second 'bafile and said third baflle, and external to said heat exchange tubes, and terminating adjacent to said plate.

6. The apparatus of claim 1, in which at least one substantially horizontal fluid diversion baffle is provided within said vessel, said fluid diversion baffle extending inwards from said plate and between said second baflie and said third bafile, and external to said heat exchange tubes, and terminating adjacent to said hot fluid inlet conduit.

7. The apparatus of claim 1, in which a plurality of staggered substantially horizontal fluid diversion baflles are provided within said vessel and between said second baflle and said third baflle, with said fluid diversion baffles alternately extending inwards from said plate and outwards from said hot fluid inlet conduit, and external to said heat exchange tubes.

8. The apparatus of claim 1, in which said vessel and said plate are cylindrical and coaxial, said conduits are cylindrical and coaxial with said vessel, and said bafiles are circular.

9. The apparatus of claim 1, in which said hot reacted fluid stream comprises eflluent converted gas from an ammonia synthesis converter, and said cold feed fluid stream comprises a gaseous mixture of hydrogen and nitrogen, said resulting combined feed stream removed from said vessel being passed to said ammonia synthesis converter.

10. An apparatus for elevated temperature and high pressure exothermic catalytic reactions which comprises a first vertically oriented vessel; a first vertical fluid circulation plate adjacent to the inner wall of said vessel; at least one catalyst bed disposed within said first vessel, the outer perimeter of said catalyst bed being defined by said first plate; means to pass a warmed feed fluid stream into said first vessel and through said catalyst bed; means to remove a hot reacted fluid stream from said first vessel; a second vertically oriented vessel; a second vertical fluid circulation plate adjacent to the inner wall of said second vessel, said second plate extending to an upper central warmed fluid transfer conduit within said second vessel and having at least one lower opening; an upper first substantially horizontal baffle within said second vessel; a second bafiie below and parallel with said first baflle, said second baifle being provided with a central opening and a plurality of spaced apart openings; a first vertical closure partition, said first partition extending between the outer edge of said first baffle and the outer edge of said second bafile; a lower third substantially horizontal 'baflle within said sec. ond vessel, said third baflle being below and parallel with said second balfle and being provided with a central opening and a plurality of spaced apart openings; a plurality of heat exchange tubes, each of said tubes extending between one of said spaced apart openings in said second baffle and one of said spaced apart openings in said third battle, a fourth baflle below and parallel with said third baflie, said fourth batfle being provided with a central opening; a second vertical closure partition, said second partition extending between the outer edge of said third battle and the outer edge of said fourth bafiie; a hot fluid inlet conduit, said inlet conduit being vertically and coaxially disposed within said second vessel and extending centrally upwards from the lower end of said second vessel through said central openings in said third and fourth batfles to the central opening in said second batfle and being contiguous with the central opening in said third bafiie; means to pass said hot reacted fluid stream from said first vessel into the lower end of said inlet conduit, whereby said hot fluid stream flows upwards through said inlet conduit, laterally outwards between said first baifle and said second baffle, downwards through said heat exchange tubes for cooling by heat exchange with said cold feed fluid stream, and laterally inwards between said third baflle and said fourth baflle; a vertically oriented cooled fluid outlet conduit, said cooled fluid outlet conduit being coaxially disposed external to said hot fluid inlet conduit and extending downwards from said central opening in said fourth bafile; means for cooled reacted fluid discharge from said vessel disposed at the lower outlet of said cooled fluid outlet conduit, said means for cooled reacted fluid discharge extending to means for removal of at least a portion of the reaction product of said exothermic catalytic reaction from said cooled reacted fluid, whereby a residual recycle fluid stream is formed; means to add makeup feed fluid to said residual recycle fluid stream, whereby a combined cold feed fluid stream is formed; means to divide said combined cold feed fluid stream into a main cold feed fluid stream and a bypass cold feed fluid stream; means to pass said main cold feed fluid stream into said first vessel external to said first plate, whereby said main cold feed fluid stream flows between said first vessel and said first plate and cools the side wall of said first vessel; means to pass said main cold feed fluid stream from said first vessel into said second vessel external to said second plate and adjacent to the upper end of said second plate, whereby said main cold feed stream flows downwards between said second vessel and said second plate thereby cooling the side wall of said second vessel, inwards through said lower opening in said second plate, upwards between said second plate and said second vertical closure partition, upwards external to said heat exchange tubes for heating of said main cold feed fluid stream, upwards between said second plate and said first vertical closure partition, and upwards through said upper central warmed fluid transfer conduit, said warmed fluid transfer conduit being coaxial with said vessel; a bypass cold feed fluid inlet conduit, said bypass conduit extending vertically downwards into said vessel from above said upper central warmed fluid transfer conduit, said bypass conduit being provided with at least one opening adjacent to its lower end; means to pass said bypass cold feed fluid stream into said bypass conduit, whereby said bypass fluid stream passes into the warmed feed fluid stream flowing upwards through said upper central warmed fluid transfer conduit; means at the upper end of said second vessel to remove the resulting combined feed stream consisting of a mixture of bypass feed fluid stream and warmed feed fluid stream; and means to pass the removed combined feed stream from said second vessel to said first vessel as said warmed feed fluid stream.

11. The apparatus of claim 10, in which said bypass cold feed fluid inlet conduit is coaxial with and terminates within said upper central warmed fluid transfer conduit, and said means to remove the resulting combined feed stream from said second vessel is above the lower end of said bypass cold feed fluid inlet conduit.

12. The apparatus of claim 10, in which said bypass cold feed fluid inlet conduit is foraminous adjacent to its lower end.

13. The apparatus of claim 10, in which the lower end of said cooled fluid outlet conduit terminates above the lower end of said hot fluid inlet conduit, and said means for cooled reacted fluid discharge from said second vessel is above said means to pass hot reacted fluid into the lower end of said inlet conduit.

14. The apparatus of claim 10, in which at least one substantially horizontal fluid diversion baflie is provided within said second vessel, said fluid diversion :baflle extending outwards from said hot fluid inlet conduit and between said second baflle and said third baflle, and external to said heat exchange tubes, and terminating adj acent to said plate.

15. The apparatus of claim 10, in which at least one substantially horizontal fluid diversion battle is provided within said second vessel, said fluid diversion baffle extending inwards from said plate and between said second baflle and said third baflle, and external to said heat exchange tubes, and terminating adjacent to said hot fluid inlet conduit.

16. The apparatus of claim 10, in which a plurality of staggered substantially horizontally fluid diversion baffles are provided within said second vessel and between said second bafile and said third baffle, with said fluid diversion bafiles alternately extending inwards from said plate and outwards from said hot fluid inlet conduit, and external to said heat exchange tubes.

17. The apparatus of claim 10, in which said second vessel and said second plate are cylindrical and coaxial, said conduits are cylindrical and coaxial with said second vessel, and said baflles are circular.

18. The apparatus of claim 10, in which said first vessel is an ammonia synthesis converter, said catalyst bed comprises an active ammonia synthesis catalyst, said hot reacted fluid stream comprises efiluent converted gas from said ammonia synthesis converter, and said cold feed fluid stream comprises a gaseous mixture of hydrogen and nitrogen, said resulting combined feed stream removed from said second vessel being passed to said ammonia synthesis converter.

19. The apparatus of claim 18, in which said active aimmonia synthesis catalyst comprises pnomoted iron oxide.

References Cited UNITED STATES PATENTS 3/1932 Pyzel 23-199 5/1933 Richardson 23-289 XR 10/1933 Tuck 23-199 XR 6/ l950 Stengel 23-198 XR 10/1961 Friend et a1. 23-199 4/1962 Schober 23-199XR 6/1962 Worn 23-288 XR 6/1962 Christensen 23-289 1/ 1968 Christensen 23-289 3/1968 Hansen 23-198 11/1968 Fayonetal 23-199 MORRIS O. WOLK, Primary Examiner B. S. RICHMAN, Assistant Examiner US. Cl. X.R. 

